Dev server startup increased from 20 seconds to 2 minutes after upgrade to 4.0.0

Describe the bug

Dev server startup time increased drastically after upgrade to 4.0.0 from 3.4.3. From 20 seconds to more than 2 minutes afte upgrade.

Did you try recovering your dependencies?

Removed all node_modules before upgrading.

Which terms did you search for in User Guide?

Did not find anything related to this issue - slow startup time of devserver.

Environment

  current version of create-react-app: 4.0.0

System:
    OS: Linux 5.4 Ubuntu 20.04 LTS
   CPU: (8) x64 Intel(R) Core(TM) i7-** CPU @ 1.80GHz
Binaries:
    Node: 14.4.0 - ~/.nvm/versions/node/v14.4.0/bin/node
    Yarn: 1.22.4 - /usr/bin/yarn
npmPackages:
    react: 16.12.0 => 16.12.0 
    react-dom: 16.13.1 => 16.13.1 
    react-scripts: 4.0.0 => 4.0.0
   
   "typescript": "4.0.3",

Steps to reproduce

TBD - it might be somehow specific to our project. Which is medium size TypeScript project.

More info

I know that this report might be hard to reproduce and I will probably need to provide more information. But there also might be more people having same issue when comparing build/startup times and we might be able to figure out why is this happening - because this seems def as a bug, as build is incredibly slow now and this is blocker for upgrading to new version.

It might be related to project setup, but I dont have idea where to start debugging issue - maybe someone from maintainers will know what might be cause. And where to start look.

[jwchang0206]

Try compile with Rust https://jwchang0206.medium.com/make-create-react-app-faster-with-rust-6c75ffa8fdfd

[mareksuscak]

Our builds have slowed down considerably, too. In my opinion, eslint should NOT be a part of the dev build at all or at least should be configurable. These days, most devs run an eslint plugin in their IDE for a more integrated dev experience anyway. Another odd default is treating all eslint warnings as errors in a CI/CD environment without any way to opt out.